An area of tough competition and high rewards; the largest or foremost of its kind. For example, Winning an Oscar put this unknown actress in the big league. The term alludes to the major (big) leagues of American baseball. [Late 1800s] Also see big time, def. 2.
1. n. a situation where competition is keen and a high level of performance is expected. (Usually plural. Referred originally to major league sports.) You’re in the big leagues now—no more penny-ante stuff.
2. and big-leaguemod. professional; big time. (From baseball.) When I’m a big-league star, I’ll send you free tickets.